Just from personal exp. I took off in a Piper tomahawk after fueling at a local airport, and did not notice that my right fuel cap was loose, all you pilots out there, yes I know preflight, my fault. On to the subject, the cap fell off, and left a 3 inch hole in the wing. The Air going over the top of the wing sucked the fuel out of the wing, I know DUH. After a 20 minute flight, there was not a drop of fuel in the wing, and I could not smell any fuel in the wing. My dad did make me pay for the fuel cap, and for the Fuel I lost. But I can assure you that there was nothing left to combust in the wing. Glad that I was running on the left tank or it would have gotten real quiet on the way home.